Process for the treatment of internal surfaces of recesses

ABSTRACT

Process for the treatment of the internal surfaces of recesses including slots, depressions, bores and the like of any required cross-sectional configuration in which the treatment is carried out by means of beam energy which is introduced into the recess.

United States Patent [5 6] References Cited UNITED STATES PATENTS [72] Inventor Dieter Konig 1a, Haderunstrasse, 8 MunichS XX 33 3 9 33 l 99 7 l/ l 77 1 11 11 "u m n" n 0 a r u" u M mmmm R mm .1 w m m Mm m MMA C P n Co mn Lmt OON e m .m m c n a d s O f e GS F fi mm 0 M16 78 6 N 66 6 r 99 9 Hum 11 1 n. l d 1 1 a xS 87 6 98 2 m W n mm a mmw A m" 33 1 HAA 8 7 o. d mm mrmmo flafi AFPP 111.111. 2523 224333 [11:11.1

[54] PROCESS FOR THE TREATMENT OF INTERNAL SURFACES 0F RECESSES 7 Claims, 15 Drawing Figs.

ABSTRACT: Process for the treatment of the internal sur- C23c 13/00 faces of recesses including slots, depressions, bores and the 1 17/933, like of any required cross-sectional configuration in which the treatment is carried out by means of beam energy which is in- 156 HE troduced into the recess.

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PATENTEUJAN 41572 SHEET 1 OF 2 Fig.1

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PROCESS FOR THE TREATMENT OF TNTERNAL SURFACES OF RECESSES The present invention concerns a process for the treatment of internal surfaces of recesses of any cross-sectional shape such as, for example, depressions, slots, blind holes or continuous bores.

When the internal surfaces of a recess in a workpiece are to be treated in a special manner without simultaneously treating the whole workpiece, a multitude of difficulties are encountered since the internal surfaces have difficult access. This is particularly the case when relatively small recesses are concerned, such as small diameter bores or perforations. Treatments which may be required for the internal surfaces of recesses are, for example, hardening, smoothing, coating with a layer of a different material etc. It may, for example, be necessary to treat the surface of a member sliding in a guide groove so as to make the surface less subject to wear. Additionally, it may, for example, be necessary with finely perforated flexible plastics material foils or plastics material panels, to consolidate the surface of the perforation holes or to harden them to such an extent so as to eliminate a gradual closing of the perforation holes by cold flux of the plastics material. A further example of possible use for the process of the invention is in the reduction of the weight of a panel of material by forming perforations and simultaneously surface hardening the internal surfaces of the perforation holes to compensate the loss of strength caused by the perforations. It is clear that in this and numerous similar cases in which treatment of the internal surfaces of recesses is required, considerable difiiculties can occur, especially when it concerns recesses of relatively large depth and small cross section.

It is an object of the invention to provide a process enabling the internal surfaces of recesses to be treated rapidly and reliably in a multitude of ways.

The object is attained in accordance with the invention by a process of the kind referred to above, which is characterized by the feature that the treatment is effected by beam energy which is introduced in the recess.

Beam energy, for example, in the form of light, laser or electron beams, has the advantage that it can be proportioned and directed with considerable accuracy and is controllable substantially without inertia. Moreover, very high performance densities may be obtained with beam energy, so that, with extremely short period actions, the required treatment effects are thus obtainable only if required over closely defined surface regions and penetration depths.

In the art, numerous processes and apparatus are known with which beam energy can be produced, directed, focused, proportioned and controlled; therefore it is unnecessary to describe processes and apparatus herein in detail.

The term treatment is to apply in this case to any required operation with which a permanent or temporary change of the properties required of the surface regions concerned can be obtained.

Often it may be advantageous for the treatment to take place during and/or directly after producing the recesses; the workpiece may thus be left in one and the same processing or treatment device.

The process in accordance with the invention may be carried out without difficulties and also in such a manner that the internal surface of the recess may be treated difi'erently in regions. For example, in a blind hole serving as axial hearing it may be required to harden the end face to a high degree, or it may be required to provide a region of particular wear resistance in a slot or a groove. By accordingly controlling the direction of the beam energy used for the treatment it is readily possible, in accordance with the process of the invention, for only predetermined regions of the internal surface of a recess to be treated.

A particularly simple embodiment of the process in accordance with the invention consists in that for the internal surfaces to be treated an energy beam at least is used which also serves to produce the recess. It is known by using energy beams such as electron beams, to carry out cutting operations and to produce recesses of optional shape; in accordance with the invention it is possible by way of one and the same energy beam, to produce the recess and also to treat its surface in a manner required. The transition from production to treatment may, for example, be effected after the recess has been produced by varying the intensity and/or the distribution of power density of the energy beam. The diameter of the energy beam may also be changed after the recess has been produced. Such measures, given by way of example, enable the recess to be first produced without difficulty with a high power density and then with reduced power density in which no longer any material reduction occurs; the surface is treated in the required manner, for example, surface hardened, smoothed or annealed.

In many cases an alternative embodiment of the process in accordance with the invention may be expedient and it is characterized by the feature that for producing the recess and for the treatment a beam energy of varying quality is used. For example, a recess may be produced with one kind of beam and subsequently the surface of the recess produced treated with an alternative kind of beam which is absorbed with diminished quality so that a uniform transition is obtained of the material properties changed by the treatment from the surface of the recess inwardly into the depth of the material.

A further particularly advantageous embodiment of the process in accordance with the invention is characterized by the feature that during the treatment an auxiliary material is supplied to the recess. The use of an auxiliary material allows numerous further methods of treatment to be realized such as the formation of a surface layer, a cooling effect, a smoothing, roughening and so forth.

Also in accordance with the invention it may be particularly favorable for an auxiliary material to be used which, with the internal surface of the recess, causes a reaction thus changing the internal surface. If, for example, an auxiliary substance is used which chemically attacks the workpiece of the material concerned, the internal surface of the recess can be roughened in this manner. An alternative possibility consists in that by suitably selecting auxiliary materials, oxide, carbide or other surface coatings may be produced on the internal surface of the recess; such embodiments are characterized by the feature that the internal surface of the recess is partially or wholly coated with the auxiliary material or a reaction product of the auxiliary material.

In many cases favorable effects may also be obtained by using an auxiliary material which enters an energy exchange with the internal surface of the recess. Such an energy exchange for example, is then obtained when an auxiliary material is used which acts as a coolant, thus especially a solid or liquid auxiliary material which has a considerable evaporation heat. With such processes a relatively rapid cooling-off or thermal quenching of the internal surface of the recess is obtainable and thereby often favorable changes of the workpiece material, such as a hardening, are brought about.

Localized use of an auxiliary material is provided in a further embodiment of the invention in a simple manner in that the auxiliary material is arranged in the action region of the beam energy and caused to enter the recess by the beam energy introduced in the recess. A particularly simple possibility of this kind is provided in accordance with the invention, in that the workpiece containing the recess to be treated has the auxiliary material inserted therein in a finely distributed form or as a coating. In this way, without any special measures, the auxiliary material comes into action only at the position where the energy beam impacts thematerial and releases and activates the auxiliary material.

An auxiliary material arranged in the action region of the beam energy can also be brought into action according to a further embodiment of the process in accordance with the invention in which the energy beam after producing in known manner the recess by means of an alternative and if required, different energy beam, is introduced in the recess; the timed interval from the end of the production operation being so selected that the temperature of the internal surface of the recess drops below a predetermined value. This method of operation is particularly expedient when the auxiliary material is to be vapor deposited on the internal wall surface of the recess and therefore a certain cooling-off of the internal wall is required. The process in accordance with the invention may, as evident, also be carried out in connection with processed and perforated workpieces. An expedient further embodiment of the process in accordance with the invention may consist in that the energy beam triggering the treatment of the internal surfaces may have a different and especially a smaller diameter than the energy beam used to produce the recess. By this means, for example, undesired overheating of the internal surfaces of the recess during the treatment operation can be avoided or at least diminished.

The supply of auxiliary material in accordance with the process of the invention may further be so effected that the auxiliary material is provided on the side of the workpiece remote from the beam in a solid or liquid state adapted to evaporate under the action of the energy beam. For example, simply a foil sheet or panel may be fed comprised partially or wholly of the auxiliary material or containing the auxiliary material. This process may be used both in completed continuous recesses, passages, ducts or perforation holes, as also in the case in which the continuous recess has first to be formed in the workpiece by action of the beam energy.

A further alternative embodiment of the process in accordance with the invention is characterized by the feature that the auxiliary material is provided on the side of the workpiece facing the beam in a solid or liquid state adapted to evaporate with the action of the energy beam. With this method of operation, favorable effects may be obtained in many cases; for example it has been found that with sufficient rapid penetration of a treating energy beam into a workpiece the gases released from the auxiliary material layer placed thereon spread explosionlike into the recess produced and forcibly eject the molten material in the direction of the beam through the continuous recess produced.

According to a still yet further embodiment of the process in accordance with the invention the auxiliary material is fed in liquid or gaseous form through a porous gas-permeable mass arranged on the workpiece. In further embodiment however of the process in accordance with the invention, the auxiliary material may be released from a porous mass which is placed in position on the side of the workpiece remote from the beam; to enable the available quantity of auxiliary material to be increased it is possible in accordance with the invention for the pores to be closed and have an elongated shape in the direction of the beam. In any case the action of the energy beam and/or the temperature increase occurring during the action of the energy beam causes the auxiliary material to be released from the porous mass, possibly by the destruction of pores. Generally it will be simply sufficient to use a mass saturated with the solid or liquid auxiliary material.

In many cases, especially when using energy in a vacuum, it is advantageous to use an auxiliary material which evaporates without trace. In such a case it may also be advantageous to use an auxiliary material which when subjected to the action of the beam energy generates a large quantity of vapor; this is particularly expedient if it is desired to ensure substantial removal of waste material during processing or treatment.

In accordance with the invention an auxiliary material may be formed of a plurality of components, especially such in which at least two components are selected so that, subject to the action of the beam energy or conditions prevailing at the treatment point, they react with one another or at least to one reaction product and assists the required treatment.

The application of the process in accordance with the invention is particularly advantageous when perforating panel or sheetlike workpieces. Since the beam energy supplies extremely high power densities and can be closely localized and controlled substantially without inertia, a large number of closely adjacent bores may be produced within a short period of time and their internal surfaces treated.

When the beam energy has been caused to act successively at several points of treatment, as is the case for example when perforating, it is possible for the process to be so conducted that the beam energy is caused to act successively at treatment points the spacing of which is greater than the spacing between two adjacent treatment points. This sudden control of the beam energy allows a more considerable cooling of the individual treatment points and hence the use of a higher overall output per surface unit of the material to be processed treated.

A load carrier beam is preferably used as beam energy and more particularly an electron beam or a considerably focused electromagnetic energy beam, especially a light or laser beam.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 shows by way of a schematic perspective view, one embodiment of the process;

FIG. 2 shows by way of a similar embodiment as FIG. I, the workpiece in section;

FIG. 3 shows schematically the treatment of a cylindrical blind hole;

FIG. 4 shows schematically the regional treatment of a cylindrical hole;

FIG. 5 shows by way of a schematic sectional view, a further embodiment;

FIGS. 6 and 7 are schematic views of possible intensity courses of an energy beam during treatment;

FIGS. 8 to 12 show by way of schematic sectional views, possible methods of keeping the auxiliary material in readiness;

FIG. 13 shows in section an apparatus for carrying out the process of the invention;

FIG. 14 shows schematically the method of operation of an alternative embodiment of the process of the invention; and

FIG. 15 shows schematically the working sequence of a per forating operation in accordance with the invention.

FIG. 1 shows a workpiece I with a recess 2 to be treated and in the form of a continuous groove of rectangular cross section. At 4a, 4b and 4c energy beams, for example electron beams, are shown schematically and by means of which beams the internal surfaces of the recess 2 may be treated. An energy beam 4a is shown which extends substantially in the longitudinal direction of the recess 2 and which, when suitably focused, generates its energy along a path extending in the workpiece 1 against the sidewalls of the grooves 2.

FIG. 2 shows, by way of a sectional view the workpiece of FIG. I, that with an inclined beaming of a suitably wide energy beam 4 it is possible to treat the whole depth of one sidewall of the recess 2.

In FIG. 3 the base of a cylindrical recess 2 is treated by means of a bundle 4 of energy beams of suitably large cross section. Of course, a beam having a smaller cross section could also be used and moved over the surface of the base.

FIG. 4 shows a workpiece l in which a recess 2 is provided in the form of a continuous bore. A slender energy beam 4 is so beamed into the bore that only a region of the cylindrical internal surface of the recess 2 is impacted and treated by the beam; it is readily seen that by suitable relative movements between workpiece l and beam 4 any regions of the internal surface can be treated.

FIG. 5 shows schematically a section through a workpiece l, in which recesses in the form of bores are to be produced and the internal surfaces of the bores are to be treated with an auxiliary material. At the left of FIG. 5 a completed bore 2 is shown, the internal surface 3 of which has a coating 6 which has been produced by the action of an auxiliary material on the heated material of the workpiece 1. In this embodiment, the auxiliary material is placed in position in the form of a layer or panel 5 on the side of the workpiece l remote from the beam 4, At the right-hand side of FIG. 5 there is shown schematically, the production of a bore with the aid of the energy beam 4. The beam 4 at the stage shown has not yet penetrated the full thickness of the workpiece I so that the internal surface of the bore produced has as yet not been treated. As soon as the beam penetrates the full thickness of the workpiece, it acts on the auxiliary material so as to cause it to evaporate and to flow through the bore 2 just produced. Thus, the desired action of the auxiliary material 5 against the internal wall surface of the bore 2 occurs. When, for example, the internal surface of the bore is to be coated by evaporation with a layer of the auxiliary material, it is expedient to reduce the beam cross section after penetrating the full thickness of the workpiece, so that the internal surface 3 of the bore 2 can become somewhat cooler.

In the case of readily evaporatable auxiliary materials, it is advisable to reduce the intensity of the beam 4. This is schematically illustrated in FIG. 6 in which the dependency of the beam intensity i upon the time t used in the process described is shown. In a first time section t the bore 2 is produced and, after the workpiece 1 has been completely bored through, the beam intensity is then reduced for a second time section t to avoid evaporating to excess the readily evaporatable auxiliary material 5.

FIG. 7 shows a possibility of allowing a certain time lapse T between the production of the recess in the time section 2, and the treatment by means of the auxiliary material in the time section t to allow the internal surface 3 of the bore to cool 05 to a predetermined temperature. Similar twoor multistage controls of the intensity and/or the beam cross section are often advantageous also when carrying out treatment without auxiliary material.

In some case of course, it is also expedient after the production of a recess with the assistance of an energy beam for its intensity not to be reduced but to be increased and generally by simultaneously changing the beam cross section, e.g. when carrying out the treatment with an auxiliary material which reacts, for example, evaporates, only at a suitably high temperature.

In the process illustrated in FIG. 5 the energy beam used to produce the bore simultaneously serves to bring about the desired treatment of the internal surface of the bore. This, of course, is not compulsive in any way. According to the process of the invention, internal surfaces of bores may also be treated which have already been produced by way of any method in the workpiece. Possibilities are known, especially when using an electron beam as energy beam, to conduct the energy beam so over the workpiece that it automatically seeks the bores and, when engaging a bore, permeates it long enough to carry out the desired treatment operation in the interior of the bore. In the case of electrically nonconductive workpieces, it is possible for example to provide on the side remote from the beam of the workpiece (in FIG. 5 thus between the workpiece l and the layer 5 of the auxiliary material), an electrically conductive sheet or evaporation, by means of which each control impulse can be tapped when the beam conducted in a search over the workpiece is incident in a bore. Such an apparatus may also be used for the purpose of indicating the complete perforation of the workpiece when producing bores.

The use of one and the same beam to produce the recess and for the desired treatment of the internal surface of the recess allows the auxiliary material also to be used as a component of the workpiece material. The schematic sectional view of FIG. 8 indicates the possibility of arranging the auxiliary material 5 in distribution in the material of the workpiece 1; this possibility is provided particularly in workpieces made of plastics material. FIG. 9 illustrates, by way of a similar sectional view as FIG. 8, the possibility of inserting the auxiliary material 5 at least in the form of a layer in the workpiece material 1. When the treatment occurs directly after producing the recess, it is also possible to supply the auxiliary material in a liquid or gaseous state to the workpiece by means of a permeable porous mass placed against the workpiece and, this is shown in FIG. 10. On the side of the workpiece l remote from the beam (the lower side in FIG. 10), a short pipe 7 of relatively large cross-sectional area is mounted so as to abut and hermetically seal the workpiece surface. A feed pipe 8 as connected to the pipe 7 for a gaseous or liquid auxiliary material. The pipe 7 is filled with a permeable porous mass 9 which sets up a high flow resistance against the auxiliary material supplied so that only a correspondingly small proportion of the entire auxiliary material, fed via the pipe 8, can escape. This is of particular importance when as energy beam 4 for the treatment, only such is used which can be maintained in a vacuum, for example, an electron beam. When using a gaseous auxiliary material the vacuum pump need pump away only relatively small quantities of gas which flows via the completed bores 2.

FIGS. 11 and 12 each illustrate by way of similar sectional views as FIGS. 5, 8, 9 and 10, an alternative possibility in accordance with the invention. In FIG. 11 the auxiliary material is released from a porous mass 10 which is placed in position on the side of the workpiece l remote from the beam (the lower side in FIG. 11); the pores ll of the mass being substantially closed and enclosing an auxiliary material. By action of an energy beam incident through a bore 2 at least one pore in the vicinity of the bore to be treated is opened and the auxiliary material contained in the pore flows through the bore concemed; the treatment operation resulting in the desired manner. When using liquid or solidified auxiliary materials, it is also possible to use a porous mass 10 without closed pores, for example, a fibrous mass which is saturated with the auxiliary substance. Accordingly it is also possible for the method of operation shown in FIG. 10 to be so modified that the short pipe socket 7 is provided without the feed pipe 8, thus, with the exception of the top being closed on all sides, the porous mass 9 contained in the pipe 7 can then also be saturated with a liquid or solid auxiliary substance.

FIG. 12 shows a further possibility in which the pores 11 of the mass 10 are elongated in the direction of the beam so that they are able to absorb a larger quantity of the normally gaseous auxiliary substance. When using masses with closed pores, the pore density relative to the surface density of the bores in the workpiece 1 must be large enough to enable the energy beam incident through a bore 2 to open at least one pore ll. Incidentally, the use of solid or liquid auxiliary substances permits at the given action point the development of a relatively large volume of vapor or gas. If this is desired when producing, for example, a recess, to eject the traces of liquified workpiece material out of the recess, it is also possible to use an auxiliary substance which per unit of volume or weight supplies a large quantity of vapor or gas. Normally it will also be expedient, when using liquid or solid auxiliary substances, to employ such auxiliary substances which evaporate without trace, for example, monomers or polymers of unsubstituted or halogenated hydrocarbons, alcohols and the like nonresidual compounds. The process in accordance with the invention may also be used with advantage for cooling when perforating panels or sheetlike workpieces, the auxiliary substance entering the bore acting as coolant. Particularly when using a solid or liquid substance as auxiliary substance considerable cooling effects can be obtained which, for example, can be used to enable a considerably greater processing power per surface unit of the workpiece to be employed and thus, when perforating, more holes per time and surface unit to be produced. Cooling as such may also be advantageous, e.g. for hardening.

FIG. 13 illustrates schematically a possible embodiment of an apparatus for carrying out the process in accordance with the invention. The perforating of a panellike or sheetlike workpiece l is shown with its lower side remote from the beam 4 the workpiece abutting against a porous mass 10 which contains the auxiliary substance, such as gas. On the upper side of the workpiece 1, facing the beam there are mounted the lower edges 14 of the sidewalls 13 of a treatment chamber 12 formed as sliding packings in which chamber the beam source 15 is accommodated. The treatment chamber 12 is connected via a socket 16 to a pump (not shown). As readily shown in FIG. 13, the gas flow entering the treatment chamber from the porous mass 10 via the bores 2 already produced is determined by the flow resistance of the porous mass 10 and the number of bores produced and situated in the treatment chamber; if necessary the free underside of the mass 10 may be provided with a sealing layer. It is seen that a certain connection exists between the performance of the pump (not shown) connected to the socket l6 and the gas pressure maintained in the treatment chamber 12. Suitable dimensioning of the cross section of the lower constricting section of the treatment chamber 12 allows the size of the gas or vapor quantity inflowing through the bores 2 already produced to be influenced within a wide range. During the processing, the processing apparatus is moved relative to the workpiece 1 in accordance with the arrow 17. It is also possible for the backing mass 10 to be moved with the treatment apparatus relative to the workpiece so that one support suffices and which is considerably smaller than the whole workpiece. In this case the support must be so fashioned that it is able to bear repeated actions of the energy beam 4. Normally, on the lower free side of the underlay mass 10 atmospheric pressure will simply prevail; it is, however, also possible to adjoin a gas chamber to the free side of the underlaid mass 10 and which gas chamber is filled with any other fluid at any other suitable pressure.

FIG. 14 shows an embodiment fundamentally similar to the embodiment of FIG. 12, in which the same energy beam is used both to produce the bores 2 in a workpiece I and to release the auxiliary substance. In this embodiment a mass 10 is laid beneath the side of the workpiece 1 remote from the beam and contains the auxiliary substance in closed pores; in FIG. 14 elongated bores similar to those in FIG. 12 are shown. The upper ends of the elongated pores are located close to the surface nearer to the beam of the underlay mass 10, so that a region l7 of the underlaid mass located at the lower end of the bore 2 produced is destroyed by the energy beam used for treatment after completely perforating the workpiece 1. The region 18 is destroyed to such an extent that the upper ends of the passagelike pores 11 are opened and the auxiliary substance contained in the pores allowed to enter the bore 2 produced. Normally the number of elongated pores located per unit surface area of underlaid mass 10 is greater than the number of bores per unit surface area produced in the workpiece, so that at least one pore per bore is opened reliably.

As already mentioned, it is desired in many cases, such as when vapor-depositing the internal surface of a recess with an auxiliary substance, to keep the temperature of the internal surfaces of a recess just produced as low as possible. Also, for reasons of strength of the workpiece material, it is often required to avoid excessive overall heating of the workpiece by the energy beam acting thereon. This excessive overall heating may be avoided by utilizing the knowledge that with a number of treatment points the energy beam is caused to act successively on treatment points, the distance of which is greater than the distance between two adjacent treatment points. The energy beam thus does not jump from one treatment point to the next adjacent treatment point but first to a more remote treatment point, so that the surrounding area of the first treatment point may cool off before a further treatment point located in the direct surrounding is treated. A very simple treatment diagram of such a kind is explained in FIG. which is a schematic plan view of the workpiece 1 provided or to be provided with perforation bores 2. The workpiece, for example, is moved in accordance with the arrow 19 relative to the energy beam used for treatment. The energy beam for example is lead in sequence over the workpiece and the sequence is indicated by the numbers in the left-hand column of the perforation holes. It will be seen that with the selected sequence only the bores 4 and 5 have been produced directly adjacent to one another. Of course, numerous kinds of nonsequential control systems of the energy beam may be used in which any size of spacing may result between successively treated treatment points. It must be noted, however, that the accuracy with which a bore position is impacted by the treatment beam becomes all the smaller the greater the nonsequential moves carried out by the beam between two successive treatment operations. The possibility described above also allows an annealing substance acting as coolant in order to obtain a further increase of energy supply permissible per time and surface unit to the workpiece I; this in turn allows accordingly smaller spacings between directly successively treated bore positions.

In the process in accordance with the invention the use of an energy beam, apart from the reasons given initially, is also of particular advantage because the energy beam has practically no mass flow so as to eliminate mutual obstruction between beam and the auxiliary substance flowing into the recess.

According to the process of the invention manifold treatments of the internal surfaces of recesses may be carried out. For example, bores in nonmetal materials may be coated by evaporation with an electrically conductive metailization; conversely, of course, bores in a metal workpiece may have an electrically insulating layer vapor-deposited thereon. Of particular importance is the process of the invention for producing plastics material filters in which the filter openings have been bored with electron beam. Hitherto it was not possible for these very fine bores to be treated on their internal surface in a desired manner, for example, by application of an auxiliary substance to be smoothed and/or mechanically strengthened. Mutual chemical reactions between auxiliary substances and/or the workpiece material allow manifold effects to occur; for example, an auxiliary substance distributed in a manner as shown in FIG. 8 in the workpiece material and comprising a mixture reacting chemically when heated can also be used to cause special effects.

The following examples further illustrate the process of the invention in a nonlimitative manner:

EXAMPLE I An aluminum plate of 1 mm. thickness was provided by means of an electron beam with bores of 0.2 mm. diameter. The action period for each bore amounted to 2 msec. with an acceleration voltage 150 kv. and a beam output of Watt. Beneath the aluminum plate as shown in FIG. 5 a polyurethane foam, foamed with oxygen, was arranged. The boring electron beam after each boring action released the contents of a few pores of the foamed material; the oxygen so released entered the highly heated bore where it produced a desired layer of aluminum oxide which has a considerably higher resistance than the pure aluminum.

EXAMPLE ll A foil of polytetrafluorethylene of 0.7 mm. thickness was placed on a copper support and perforated with an electron beam. The beam was impulse controlled; each impulse of 20- microsecond duration produced a hole (perforation) of about 0.8 mm. diameter. The acceleration voltage amounted to kv., the beam current amounted to 10 ma. The intensity of each electron beam impulse was controlled substantially according to the pattern of FIG. 6, so that in the second half of the overall impulse duration the beam current dropped to about 2 mm. Moreover, in the second half of the impulse duration the beam diameter was reduced by about half. A clean vapor-depositing of the internal wall surfaces with copper resulted.

EXAMPLE III A sheet of 0.3 mm. thickness of stainless steel was perforated with electron beam impulses of I50 kv., 25 ma. and 15 used; the diameter of the holes produced amounted to 0.33 mm. Beneath the steel sheet there was placed a disc pressed from aluminum oxide. In the perforation holes there resulted an insulation layer of vapor-deposited aluminum oxide of about 0.0005 to 0.005 mm. thickness.

EXAMPLE IV A hardenable steel sheet of 0.3 mm. thickness was perforated with electron beam impulses of 140 kv., ma. and 45 sec. duration; the diameter of the holes produced was 0.125 mm. Beneath the steel sheet there was placed a polyvinyl chloride fiber material of 1.2 mm. thickness saturated with methyl alcohol and provided on the surface not supported against the steel sheet with a sealing surface layer. The extensive cooling action of the methyl alcohol vapor entering the bore after it was produced caused a surface hardening of the internal wall surface of the perforation holes, thus the thickness of the layer applied was about 0.015 to 0.02 mm.

EXAMPLE V A sheet of synthetic leather of 0.5 mm. thickness on a polyvinyl chloride base was perforated with electron beam 2 of 125 kv., 7 ma. and 12 1sec. duration; the diameter of the holes produced was about 0.03 mm. Beneath the synthetic leather sheet there was placed a polyvinyl chloride fibrous material of 1.5 mm. thickness which was saturated with ethyl alcohol and on the side not supported against the synthetic leather sheet was provided with a sealing surface layer. The cooling action of the ethyl alcohol vapor entering each bore produced allowed the obtainable surface density of the perforation holes to be increased from 2,000 holes per cm. to 4,000 per cm. and the applicable impulse frequency could be increased from 500 holes per second to 2,000 holes per second.

Other embodiments are possible without departing from the scope of the invention. It is especially clear that, in accordance with the process of the invention, recesses of optional shape and cross section form can be treated.

What we claim is:

1. A process for treating internal surfaces of recesses in workpieces, including slots, depressions, bores, and the like by means of beamed radiant energy in order to effect a permanent change in the condition of said internal surfaces, comprising placing the workpiece which contains the recess to be treated adjacent to a material which has an auxiliary substance which is in an inactive state incorporated therein in finely divided form, and applying beamed radiant energy to the said auxiliary substance of an intensity sufficient to locally activate and release the said auxiliary substance to enable it to enter the said recesses and to alter the condition of the internal surfaces thereof 2. A process for treating internal surfaces of recesses in workpieces, including slots, depressions, bores, and the like by means of beamed radiant energy in order to effect a permanent change in the condition of said internal surfaces, comprising placing a carrier member consisting of a permeable mass containing an auxiliary substance which is in an inactive liquid or gaseous state dispersed throughout the carrier member adjacent to one side of the workpiece which contains the recess to be treated, and applying beamed radiant energy of an intensity sufficient to activate and release the said auxiliary substance at the opposite side of said workpiece to extend through said recess and to act on the auxiliary substance contained in the carrier member located on the opposite side of the workpiece, the auxiliary substance which is locally released and activated by the beamed radiant energy being caused thereby to enter said recesses to act on the internal surfaces thereof and to alter the condition of said internal surfaces.

3. A process for treating internal surfaces of recesses in workpieces, including slots, depressions, bores. and the like by means of beamed radiant energy in order to effect a permanent change in the condition of said internal surfaces, comprising placing a carrier member consisting of a porous mass containing within its pores an auxiliary substance which is in an inactive state adjacent to one side of the workpiece which contains the recess to be treated, and applying beamed radiant energy at the opposite side of said workpiece to extend through said recess and to act on the auxiliary substance located on the opposite side of the workpiece, the beamed radiant energy being applied at an intensity sufficient to activate and release the said auxiliary substance from said pores and to cause it to enter the said recesses and to act on and alter the condition of the internal surfaces thereof.

4. A process in accordance with claim 3 in which the said pores are closed pores, and in which said carrier member consists of a material which is destroyed when subjected to the beamed radiant energy.

5. A process in accordance with claim 3 in which the substance contained in said pores is oxygen and in which the beamed radiant energy applied thereto keeps the temperature of the internal surfaces of the recess sufficiently high to permit reaction of the workpiece material with the oxygen released from the pores to produce an oxide coating on the internal surface of the recess.

6. A process for treating internal surfaces of recesses in workpieces, including slots, depressions, bores, and the like by means of beamed radiant energy in order to effect a permanent change in the condition of the internal surfaces, comprising placing an auxiliary substance which is in an inactive state adjacent to the recess to be treated and applying beamed radiant energy to the said auxiliary substance of an intensity sufficient to activate and release the said auxiliary substance to enable it to enter the said recesses and to alter the condition of the internal surfaces thereof, the auxiliary substance comprising at least two components which react with one another under the action of the beamed radiant energy to form at least one reaction product which alters the condition of the said internal surfaces.

7. A process for successively treating internal surfaces of a plurality of spaced recesses in workpieces, including slots, depressions, bores, and the like by means of beamed radiant energy in order to effect a permanent change in the condition of said internal surfaces, comprising placing an auxiliary substance which is in an inactive state adjacent to the recesses to be treated and applying beamed radiant energy to the said auxiliary substance of an intensity sufficient to activate and release the said auxiliary substance to enable it to enter the said recesses and to alter the condition of the internal surfaces thereof, the beamed radiant energy being applied successively at recesses the distance between which is greater than the distance between adjacent recesses 

2. A process for treating internal surfaces of recesses in workpieces, including slots, depressions, bores, and the like by means of beamed radiant energy in order to effect a permanent change in the condition of said internal surfaces, comprising placing a carrier member consisting of a permeable mass containing an auxiliary substance which is in an inactive liquid or gaseous state dispersed throughout the carrier member adjacent to one side of the workpiece which contains the recess to be treated, and applying beamed radiant energy of an intensity sufficient to activate and release the said auxiliary substance at the opposite side of said workpiece to extend through said recess and to act on the auxiliary substance contained in the carrier member located on the opposite side of the workpiece, the auxiliary substance which is locally released and activated by the beamed radiant energy being caused thereby to enter said recesses to act on the internal surfaces thereof and to alter the condition of said internal surfaces.
 3. A process for treating internal surfaces of recesses in workpieces, including slots, depressions, bores, and the like by means of beamed radiant energy in order to effect a permanent change in the condition of said internal surfaces, comprising placing a carrier member consisting of a porous mass containing within its pores an auxiliary substance which is in an inactive state adjacent to one side of the workpiece which contains the recess to be treated, and applying beamed radiant energy at the opposite side of said workpiece to extend through said recess and to act on the auxiliary substance located on the opposite side of the workpiece, the beamed radiant energy being applied at an intensity sufficient to activate and release the said auxiliary substance from said pores and to cause it to enter the said recesses and to act on and alter the condition of the internal surfaces thereof.
 4. A process in accordance with claim 3 in which the said pores are closed pores, and in which said carrier member consists of a material which is destroyed when subjected to the beamed radiant energy.
 5. A process in accordance with claim 3 in which the substance contained in said pores is oxygen and in which the beamed radiant energy applied thereto keeps the temperature of the internal surfaces of the recess sufficiently high to permit reaction of the workpiece material with the oxygen released from the pores to produce an oxide coating on the internal surface of the recess.
 6. A process for treating internal surfaces of recesses in workpieces, including slots, depressions, bores, and the like by means of beamed radiant energy in order to effect a permanent change in the condition of the internal surfaces, comprising placing an auxiliary substance which is in an inactive state adjacent to the recess to be treated and applying beamed radiant energy to the said auxiliAry substance of an intensity sufficient to activate and release the said auxiliary substance to enable it to enter the said recesses and to alter the condition of the internal surfaces thereof, the auxiliary substance comprising at least two components which react with one another under the action of the beamed radiant energy to form at least one reaction product which alters the condition of the said internal surfaces.
 7. A process for successively treating internal surfaces of a plurality of spaced recesses in workpieces, including slots, depressions, bores, and the like by means of beamed radiant energy in order to effect a permanent change in the condition of said internal surfaces, comprising placing an auxiliary substance which is in an inactive state adjacent to the recesses to be treated and applying beamed radiant energy to the said auxiliary substance of an intensity sufficient to activate and release the said auxiliary substance to enable it to enter the said recesses and to alter the condition of the internal surfaces thereof, the beamed radiant energy being applied successively at recesses the distance between which is greater than the distance between adjacent recesses. 